101 Facts About Ageing #30: Skin Ageing

As Daniel Patrick Moynihan, an American sociologist, politician, and diplomat once said: “Everyone is entitled to his own opinion, but not his own facts”. And we wholeheartedly agree. A shared set of facts is the first step to building a better world with longevity for all. In that spirit, we are creating a series that covers 101 indisputable facts about ageing, health and longevity.

Skin ageing is not only cosmetic but also functional. With age, the skin becomes thinner, less elastic and less firm, making it more fragile. These changes also lead to the sagging of the skin and the formation of wrinkles. Aged skin also takes longer to heal, and is generally drier and duller than young skin. Aged skin is more susceptible both to benign growths and to skin cancer.

The loss of firmness and elasticity is due to a reduction in two key molecules – collagen and elastin – within the dermis (the middle layer of the skin). These are long, structural proteins that act like scaffolding to hold cells together. With age, these molecules become increasingly damaged and their production by cells declines, making the scaffolding more fragmented. These proteins are also increasingly bonded to each other by molecules called advanced glycation end products (A.G.Es), which are formed when glucose molecules react with proteins or lipids in a process called glycation. When these structural proteins are linked in this way, the elasticity of the tissue as a whole decreases.

The transfer of moisture from the dermis to the epidermis slows with age, while sebaceous (oil) glands and fat cells begin to shrink. These changes make the skin drier, duller and thinner.

Collagen and elastin molecules sustain damage from a variety of sources, both from within and outside the body. Free radicals (which are normal products of cellular metabolism) and A.G.Es are important causes of damage from within the body, while ultraviolet light is a significant external cause of damage. The DNA of cells within the skin also sustains damage, which leads to an increased production of free radicals, defective protein production and an increased risk of developing skin cancers. DNA damage also leads to the death of stem cells within the skin. Stem cells are capable of dividing and giving rise to multiple types of cell, and are therefore essential for tissue maintenance and repair. The main source of DNA damage is usually ultraviolet radiation.